CN113403538A

CN113403538A - High-contact fatigue performance wheel and production method thereof

Info

Publication number: CN113403538A
Application number: CN202110670673.8A
Authority: CN
Inventors: 国新春; 陈刚; 张磊; 邓荣杰; 王翔; 宁珅
Original assignee: Baowu Group Masteel Rail Transit Materials Technology Co Ltd
Current assignee: Baowu Group Masteel Rail Transit Materials Technology Co Ltd
Priority date: 2021-06-17
Filing date: 2021-06-17
Publication date: 2021-09-17

Abstract

The invention provides a wheel with high contact fatigue performance and a production method thereof, and the wheel comprises the following components: c: 0.55-0.65%, Si: 0.15-0.30%, Mn: 0.40-1.2%, Cr: 0.10 to 0.25%, Al: 0.02-0.03%, P: less than or equal to 0.010 percent, S: 0.020-0.035%, V0.10-0.20%; T.O: less than or equal to 10ppm, [ H ]: 1.5ppm or less, [ N ]: 80-120ppm, and the balance of Fe and inevitable impurity elements. Compared with the prior art, the high contact fatigue wheel steel produced by adopting the specific components and the reasonable preparation method ensures that the surface contact fatigue resistance of the prepared wheel is obviously improved through a certain heat treatment process.

Description

High-contact fatigue performance wheel and production method thereof

Technical Field

The invention belongs to the technical field of railway wheel preparation, and particularly relates to a high-contact fatigue performance wheel and a production method thereof.

Background

The working environment of the wheel is complex and severe, and the main failure modes are tread stripping, pit stripping caused by contact fatigue, fatigue stripping and the like. The material is generally required to have good toughness and wear resistance, so the performance of the material can be reflected by the contact fatigue of the material. In view of the complex working environment of the wheel, many scholars also make relevant studies on contact fatigue:

patent application "steel for wheel", published under 24.7.2013, of new-day iron-on-gold corporation in china, publication no: CN 103221561A, which discloses a wheel steel with excellent balance of performances such as wear resistance, contact fatigue resistance, thermal damage resistance and the like and long service life, and the wheel steel comprises 0.65-0.84 percent of C by weight; 0.02-1.00% of Si; 0.50-1.90% of Mn; 0.02-0.50% of Cr; v is 0.02-0.20; s is less than or equal to 0.04; p is less than or equal to 0.05; cu is less than or equal to 0.20; ni is 0.20 or less, satisfies [34 or less and 2.7+29.5 XC +2.9 XSI +6.9 XMN +10.8 XCr +30.3 XMO +44.3 XV or less and 43, and [0.76 XSexp (0.05 XC). times.exp (1.35 XSI). times.exp (0.38 XMN). times.exp (0.77 XCr). times.exp (3.0 XMO). times.exp (4.6 XV) or less ]. However, the invention focuses on the optimal design and adjustment of the components of the wheel steel, so that the key factors influencing the comprehensive performance of the wheel steel cannot be rapidly identified, and the conventional tread forced cooling process is adopted, and some parts of the wheel have undesirable non-pearlite structures.

Disclosure of Invention

The invention aims to provide a wheel with high contact fatigue resistance and a production method thereof, and provides a wheel with high yield ratio and obviously improved surface contact fatigue resistance by optimizing Cr, V and Al microalloying, heat treatment process and the like, wherein the surface contact fatigue peeling resistance of the wheel is obviously superior to that of the conventional wheel.

The specific technical scheme of the invention is as follows:

a wheel with high contact fatigue performance comprises the following components in percentage by mass:

c: 0.55-0.65%, Si: 0.15-0.30%, Mn: 0.40-1.2%, Cr: 0.10 to 0.25%, Al: 0.02-0.03%, P: less than or equal to 0.010 percent, S: 0.020-0.035%, V0.10-0.20%; T.O: less than or equal to 10ppm, [ H ]: 1.5ppm or less, [ N ]: 80-120ppm, and the balance of Fe and inevitable impurity elements.

Further, Al/[ N ]: 2.0 to 4.0.

The production method of the wheel with high contact fatigue performance provided by the invention comprises the steps of heating;

the heating is specifically as follows: the total time of preheating, heating and soaking the steel billet in the heating furnace is controlled to be 5.0-10.0 h.

Soaking, wherein the temperature is controlled to be 1230-1280 ℃, the heating and heat preservation time is more than or equal to 4h, the purpose is to ensure that the inside and the outside of the billet are uniformly heated and the rolling is easy, the billet with the temperature higher than 1280 ℃ has the risk of overburning, and the deformation resistance of the billet with the temperature lower than 1230 ℃ is large and is not beneficial to the rolling;

the production method further comprises rolling, the rolling being performed after the heating;

the rolling is specifically as follows: the initial rolling temperature is 1120-1180 ℃, the final rolling temperature is 930-980 ℃, and the rolling process is finished at the temperature, so that the continuous strip type A impurities can be crushed to form discontinuous short and small type A impurities.

Further, slowly cooling after rolling;

the slow cooling specifically comprises the following steps: cooling the rolled steel plate to 600-650 ℃ through a cooling bed, and entering a pit for slow cooling; the slow cooling time is more than or equal to 8 hours; the purpose is to discharge a large amount of gas H element in the steel billet and to make the residual H uniform.

The manufacturing method further includes: loading the blank wheel formed by rolling into a furnace, and heating for 2.5-4.0h at 870-910 ℃ for full austenitizing; discharging the wheel obtained by full austenitizing, transferring the wheel to a quenching table, accelerating the cooling of the metal in the wheel rim to below 550 ℃ at a cooling speed of 2-5 ℃/s, and then tempering the wheel.

The tempering treatment is carried out at 480-520 ℃ for more than or equal to 4 hours;

and finally, carrying out machining and tread profiling procedures to obtain the finished product wheel.

The microstructure of the wheel with high contact fatigue performance produced by the invention is pearly-lustre and ferrite, and the volume proportion of the ferrite is less than or equal to 4 percent; the maximum length of the A-type inclusions is less than or equal to 33 mu m; the yield ratio is obviously improved.

The invention has the following elements and functions and the process design principle:

c: c is the most basic effective strengthening element in steel and the most effective element influencing hardenability, the content of C cannot be lower than 0.55 percent in order to ensure the sufficient strength and hardenability of the wheel steel, and the content of C is determined to be 0.55-0.65 percent because the wheel steel needs to ensure the toughness and cannot be higher than 0.65 percent.

Si: si is a deoxidizer, and can improve the hardenability of the wheel steel by simultaneously improving the strong hardness of the steel through solid solution strengthening, the content of Si is not less than 0.15 percent, but the excessive Si increases the activity of C, promotes the decarburization and graphitization tendency of the steel during rolling and heat treatment, makes the carburized layer easy to oxidize, and therefore the content of Si is not more than 0.30 percent. The Si content is controlled to be 0.15-0.30%.

Mn: mn can be dissolved in ferrite, so that the hardness and strength of the ferrite and austenite in the steel are improved, and meanwhile, the stability of an austenite structure can be improved, and the hardenability of the steel is obviously improved. However, excessive Mn lowers the plasticity of the steel, and the toughness of the steel deteriorates during hot rolling. The Mn content is controlled to be 0.40-1.2%.

Cr: cr can improve the hardenability and strength of steel, Cr can also reduce the activity of C, can reduce the decarburization tendency of the steel surface in the heating, rolling and heat treatment processes, and is beneficial to obtaining high fatigue resistance, so the Cr content cannot be lower than 0.10 percent, excessively high Cr can reduce the toughness of steel, simultaneously a large amount of carbide appears in a carburized layer structure to influence the performance of the carburized layer, and the Cr content cannot be higher than 0.25 percent. The Cr content is controlled to be 0.10-0.25%.

V: vanadium is an important strong carbonitride forming element in wheel steel, and can form clearance type VC and V in the steel through heating dissolution and cooling precipitation₄C₃And nitrogen-rich V (C, N) second phase particles, and strong precipitation strengthening and fine grain strengthening are generated, so that the effect of obviously improving the yield strength is achieved. In addition, the formation of the vanadium-containing second phase particles promotes the formation of proeutectoid ferrite due to poor carbon and smaller lattice mismatch degree with the ferrite in the micro-area around the particles, so that the effect of moderately improving the wear rate is achieved, and the aims of coordinating the competitive relationship between contact fatigue and wear and improving the surface contact fatigue resistance of the wheel are fulfilled. The vanadium content is set to be 0.10-0.20%, the reason is that on one hand, if the vanadium content exceeds the value, the higher heating temperature is needed to generate the obvious strengthening effect, otherwise, the V microalloying is greatly limited to improve the strength and even generate the negative effect under the influence of double factors of low solid solution V content and low matrix carbon content; on the other hand, too low a vanadium content does not exert a significant precipitation strengthening effect, and even if the heat treatment system is improper, vanadium causes a decrease in strength due to the abstraction of carbon in the matrix.

Al: al is an effective deoxidizer, and forms AlN refined grains, and when the Al content is less than 0.020%, the effect is not obvious, and when the Al content is more than 0.030%, coarse inclusions are easily formed, and the performance of the steel is deteriorated. Therefore, the Al content should be controlled to 0.020-0.030%.

[ N ]: can form compound with Al to refine crystal grains, reasonable Al/N has obvious effect on grain refinement, and excessive N can form continuous casting defects such as bubbles. Therefore, the content of [ N ] should be controlled to 80 to 120 ppm. While controlling Al/[ N ]: 2.0 to 4.0.

P and S: the sulfur is easy to form MnS inclusion with manganese in the steel, so that the steel is hot-brittle, but the addition of a small amount of S can obviously improve the cutting performance of the wheel steel while not affecting the performance of products, and the MnS has the effect of refining grains; p is an element with strong segregation tendency, increases the cold brittleness of steel, reduces the plasticity and is harmful to the uniformity of the product structure and performance. Controlling P to be less than or equal to 0.010 percent, and S: 0.020-0.035%.

T.O and [ H ]: forming oxide inclusions in the steel by the T.O, and controlling the T.O to be less than or equal to 10 ppm; [H] white spots are formed in steel, the product performance is seriously influenced, and the [ H ] is controlled to be less than or equal to 1.5 ppm.

In the production process, V exists in steel as replacement solute atoms, the size of the V atoms is larger than that of iron atoms, the V atoms are easy to be deviated on dislocation lines, and a strong dragging effect is generated on dislocation climbing, so that recrystallization nucleation is inhibited, and the steel has a strong prevention effect on recrystallization. The V element is heated to the temperature above the austenitizing temperature, so that the solute in the crystal has enough time to migrate to the newly formed MC on the dislocation and inoculate a new crystal boundary, thereby obtaining finer crystal grains when quenching is carried out again. The V dissolved in the matrix precipitates V (C, N) second phase particles which are coherent or semi-coherent with the matrix, and a strong precipitation strengthening effect is generated, so that the yield strength is obviously improved.

Compared with the prior art, the high contact fatigue wheel steel produced by adopting specific components and a reasonable preparation method has the advantages that the ratio of the yield strength to the tensile strength is obviously improved through a certain rolling and heat treatment process, the yield strength of the wheel is more than or equal to 640MPa, the tensile strength of the wheel is more than or equal to 1040MPa, the yield ratio of the wheel is more than or equal to 0.61, the average hardness of a wear part is more than or equal to 295HB, and the surface contact fatigue resistance of the prepared wheel is obviously improved.

Drawings

FIG. 1 is a microstructure of the wheel material of example 1, pearlite + 4% ferrite;

FIG. 2 is a microstructure of the wheel material of comparative example 1, which is pearlite + a small amount of bainite + 2% ferrite;

FIG. 3 is a microstructure of the wheel material of example 2, pearlite + 2% ferrite;

FIG. 4 is a microstructure of the wheel material of comparative example 2, pearlite + 3% ferrite;

FIG. 5 is a microstructure of the wheel material of example 3, pearlite + 2% ferrite;

fig. 6 is a microstructure of the wheel material of comparative example 3, pearlite + 4% ferrite.

Detailed Description

The technical solution of the present invention is further described in detail below with reference to examples and figures.

Further, Al/[ N ]: 2.0 to 4.0.

The production method of the wheel with high contact fatigue performance comprises the following process flows:

smelting by adopting an electric arc furnace, LF refining, RH vacuum treatment, continuous casting, saw cutting, heating, rolling, heat treatment and processing;

wherein the soaking temperature of the produced continuous casting billet in a heating furnace is controlled to be 1230-1280 ℃ after the continuous casting billet is sawed; the total time of preheating, heating and soaking is controlled to be 5.0 h-10.0 h; heating at 1230-1280 ℃ and keeping the temperature for more than or equal to 4 hours; rolling round steel, wherein the initial rolling temperature is as follows: 1120-1180 ℃, the finishing temperature is 930-980 ℃, the rolled steel is cooled to 600-650 ℃ by a cooling bed and then enters a pit for slow cooling, and the slow cooling time is more than or equal to 8 hours; the heat treatment process of the wheel steel comprises the following steps: loading the blank wheel formed by rolling into a furnace, heating for 2.5-4.0h at 870-910 ℃ to fully austenitize; and discharging the wheel obtained by full austenitizing, transferring the wheel to a quenching table, accelerating the cooling of the metal in the wheel rim to below 550 ℃ at a cooling speed of 2-5 ℃/s, tempering the wheel at 480-520 ℃ for more than or equal to 4 hours, and then performing machining, tread profiling and other procedures to obtain the finished wheel.

Example 1 to example 3

A wheel with high contact fatigue performance comprises the following components in percentage by mass: as shown in table 1 below, the balance not shown in table 1 is Fe and inevitable impurities.

Comparative examples 1 to 3

A wheel comprises the following components in percentage by mass: as shown in table 1, the balance not shown in table 1 is Fe and inevitable impurities.

TABLE 1 inventive and comparative examples chemical composition ((unit: [ N ] is ppm, remaining wt%))

860 wheels described in the above examples 1 to 3 and comparative examples 1 to 3 were produced according to the above production method, with specific parameters as shown in tables 2 and 3:

TABLE 2 Steel Rolling production Process parameters

TABLE 3 Heat treatment Process parameters for vehicle wheels

The wheels produced in each example and comparative example obtained tensile mechanical property test and brinell hardness test yield strength and average hardness at wear, see table 4; a wear performance and contact fatigue performance comparison test is carried out on an MMS-2A type microcomputer control testing machine, under the same test conditions (in the test process, a main sample is a wheel sample prepared in the embodiment and a comparative wheel sample, matched samples are U71Mn steel rail samples with the same hardness, the diameters of the main sample and the matched samples are both 60mm, the wear test comprises a group of 3 sets of samples, the rotating speed of the main sample is 360rpm, the rotating speed of the matched samples is 400rpm, the corresponding rotational slip rate is 0.75%, the contact stress is 1100MPa, the cycle number is 50 ten thousand times, the contact fatigue test comprises a group of 6 sets of samples, the rotating speed is 2000rpm, the corresponding rotational slip rate is 0.3%, the contact stress is 1100 and 1500MPa, the lubricating is carried out by using 20# engine oil), the wear performance comparison is shown in a table 5, and the wheel contact fatigue performance comparison is shown in a table 6.

TABLE 4 wheel Strength and hardness

TABLE 5 comparison of wear Performance of wheels from examples 1-3 and comparative examples 1-3

TABLE 6 comparison of contact fatigue properties of wheels for examples 1-3 and comparative examples 1-3

The abrasion weight loss of the wheel is obviously reduced compared with that of a comparative wheel, and the maximum diameter difference of the sample after the wheel material of the embodiment is abraded is obviously smaller than that of the comparative wheel. Meanwhile, the cycle frequency of the contact fatigue of the wheel of the invention is obviously higher than that of the comparative wheel, which shows that the rolling contact fatigue resistance of the wheel material of the embodiment is better than that of the comparative wheel.

The invention provides a wheel with high yield ratio and obviously improved surface contact fatigue resistance and a preparation method thereof, and the prepared wheel has obviously better surface contact fatigue peeling resistance than the traditional wheel.

Claims

1. The wheel with high contact fatigue performance is characterized by comprising the following components in percentage by mass:

2. The wheel of claim 1, wherein the ratio of Al/[ N ]: 2.0 to 4.0.

3. The wheel with high contact fatigue performance according to claim 1 or 2, wherein the microstructure is pearly-lustre and ferrite, and the volume ratio of ferrite is less than or equal to 4%.

4. A method for producing a wheel with high contact fatigue performance according to any one of claims 1 to 3, wherein the method comprises heating, in particular: uniformly heating at 1230-1280 ℃ for more than or equal to 4 hours.

5. The production method according to claim 4, wherein the heating, the billet heating and the soaking are performed in a heating furnace for a total time of 5.0h to 10.0 h.

6. The production method according to claim 4 or 5, characterized in that it further comprises rolling, the start rolling temperature: 1120-1180 ℃ and 930-980 ℃ of finish rolling temperature.

7. The production method according to any one of claims 4 to 6, characterized by further comprising slow cooling, wherein the rolled steel plate is cooled to 600-650 ℃ by a cooling bed and then is put into a pit for slow cooling, and the slow cooling time is not less than 8 hours.

8. The production method according to any one of claims 4 to 7, characterized in that the manufacturing method further comprises: loading the blank wheel formed by rolling into a furnace, and fully austenitizing at the temperature of 870 ℃ and 910 ℃; discharging the wheel obtained by full austenitizing, transferring the wheel to a quenching table, accelerating to cool the metal in the wheel rim to below 550 ℃ at a cooling speed of 2-5 ℃/s, and then tempering.

9. The method as claimed in claim 8, wherein the tempering treatment is 480 ℃ and 520 ℃ for 4 hours or more.